The analysis published Thursday in “Environmental Research Letters” compared the future sustainability of high speed rail with plane and car travel.

Researchers determined that a fully-operational high-speed rail system would use less energy and emit fewer greenhouse gasses. That’s true even when they accounted for more fuel-efficient cars and planes in the future.

Mikhail Chester, who co-authored the study, said that “even at low occupancy, a future train against a future plane trip, against a future automobile trip, the train still tends to have a lower greenhouse gas footprint than these other modes.”

Researchers considered different scenarios, such as different levels of ridership and renewable energy use when calculating emissions of greenhouse gases and air pollutants.